Rod reduction instrument feedback system

ABSTRACT

Various implementations include rod reduction instruments, spinal fixation monitoring systems, and related methods. Certain implementations include a rod reduction instrument that is adapted for use with a spinal fixation system and includes a sensor configured to detect a load exerted by a rod reducer on a spinal rod, along with a reduction feedback system that provides an indicator of the load exerted by the rod reducer on the spinal rod.

PRIORITY CLAIM

This application claims the benefit of U.S. Provisional Application Ser.No. 63/239,148, filed on Aug. 31, 2021, which is incorporated herein byreference in its entirety.

TECHNICAL FIELD

This disclosure generally relates to medical devices. More particularly,the disclosure relates to the field of spinal surgery and spinalfixation devices.

BACKGROUND

Spinal fixation constructs are utilized to provide stability to thespine. Most often the fixation construct is used as an adjunct to fusionsurgery during which adjacent vertebrae are prepared to facilitate bonegrowth between them. Because motion between the vertebrae tends toinhibit bone growth, the fixation constructs are employed to preventmotion so that bone can grow and achieve a solid fusion. When theposition of one or more vertebrae must be adjusted to restore a morenatural alignment of the spinal column, the fixation construct alsoserves to maintain the new alignment until fusion is achieved.

Fixation constructs of various forms are known in the art, of which, rodbased fixation constructs are one of the most common. Typically a rodbased construct includes multiple anchors that are coupled to a portion(e.g. the posterior elements) of two or more vertebrae and thenconnected by a fixation rod. The anchors further include a rod housingin which the fixation rod is captured and locked. The rod housing may befixed, pivotably or rotatably coupled to the anchor portion andgenerally includes a pair of upstanding arms separated by a rod channel.When constructing the fixation construct the surgeon must align and seatthe rod in the rod channel of each anchor, an undertaking that isgenerally referred to as “reduction.” Reduction can be a challenge,particularly when one or more of the vertebrae to be connected are outof alignment with other vertebrae, and the reduction distance and forcerequirements can vary greatly from anchor to anchor. Conventionalreduction procedures are heavily reliant upon the surgeon (oroperator's) expertise in judging the load applied by each rod reducer onthe spinal rod. In multi-level fixation procedures involving multiplevertebrae, it can be particularly challenging for the surgeon todetermine which rod reducer(s) are properly loaded while engaged withthe spinal rod.

SUMMARY

The needs above, as well as others, are addressed by embodiments of rodreduction instruments, spinal fixation monitoring systems, and relatedmethods described in this disclosure. All examples and featuresmentioned below can be combined in any technically possible way.

Various implementations include rod reduction instruments, spinalfixation monitoring systems, and related methods. Certainimplementations include a rod reduction instrument that is adapted foruse with a spinal fixation system and includes a sensor configured todetect a load exerted by a rod reducer on a spinal rod, along with areduction feedback system that provides an indicator of the load exertedby the rod reducer on the spinal rod.

In particular aspects, a rod reduction instrument adapted for use with aspinal fixation system includes: a rod reducer having a proximal end anda distal end, where the distal end of the rod reducer is configured toengage a spinal rod for seating the spinal rod into a pedicle screwreceiver; a sensor configured to detect a load exerted by the rodreducer on the spinal rod during seating of the spinal rod in thepedicle screw receiver; and a reduction feedback system coupled with thesensor, the reduction feedback system configured to: receive load dataindicating the load exerted by the rod reducer on the spinal rod fromthe sensor; and provide an indicator of the load data that is detectableby an operator of the rod reduction instrument.

In additional particular aspects, a method includes providing feedbackto an operator during a spinal fixation procedure, the spinal fixationprocedure including engaging a spinal rod with a rod reducer to seat thespinal rod into a pedicle screw receiver. The method can furtherinclude: receiving, from a sensor, load data indicating a load exertedby the rod reducer on the spinal rod during seating of the spinal rod inthe pedicle screw receiver; and providing an indicator of the load datathat is detectable by the operator during the spinal fixation procedure.

In further particular aspects, a spinal fixation monitoring system foruse in a spinal fixation procedure includes: a plurality of rodreduction instruments adapted for use with a spinal fixation system,each of the rod reduction instruments including: a rod reducer having aproximal end and a distal end, wherein the distal end of the rod reduceris configured to engage a spinal rod for seating the spinal rod into acorresponding pedicle screw receiver; and a sensor configured to detecta load exerted by the rod reducer on a portion of the spinal rod duringseating of the spinal rod in the pedicle screw receiver; and a reductionfeedback system coupled with the sensor of each of the rod reductioninstruments, the reduction feedback system configured to: receive loaddata indicating the load exerted by each rod reducer on the portion ofthe spinal rod from a corresponding one of the sensors; and provide anindicator of the load data for at least one of the rod reducers in theplurality of rod reduction instruments, the indicator being detectableby an operator of the plurality of rod reduction instruments.

In other particular aspects, a spinal fixation system includes: a firstbone anchor including a first pedicle screw and a receiver; a rodconfigured to be seated within the receiver of the first bone anchor; aninstrument configured to couple to the first bone anchor; and a sensorcoupled to the instrument and configured to determine data relating toat least one of: the first bone anchor, the rod or the instrument.

Implementations may include one of the following features, or anycombination thereof.

In certain examples, the rod reduction instrument further includes ahousing mounted to the proximal end of the rod reducer, where thereduction feedback system is disposed within the housing.

In some cases, the housing is: a) modular and/or disposable, b) mountedto the existing nut and is disposable, or c) mounted to any portion ofthe rod reducer.

In particular implementations, the reduction feedback system includes aprocessor and memory, the memory storing instructions which whenexecuted, cause the processor to: compare the load data with a loadthreshold for the rod reducer; and provide an indicator that the loaddata satisfies or does not satisfy the load threshold for the rodreducer.

In certain aspects, the load data at least partially represents anamount of torque applied to a lock screw during tightening of the lockscrew within the pedicle screw receiver and a compressive force appliedto the rod reducer, wherein the indicator that the load data satisfiesor does not satisfy the load threshold includes an indicator of anamount that the compressive force applied to the spinal rod should bemodified to satisfy the load threshold for the rod reducer, where theload threshold is based at least in part on a model that correlatesclinical data representing patient-specific bone quality with screwpullout.

In certain cases, the load threshold defines a maximum acceptable loadexerted by the rod reducer on the spinal rod during seating of thespinal rod in the pedicle screw receiver, wherein the maximum acceptableload is: a) approximately 50 pounds to approximately 250 pounds, b)approximately 25 pounds to approximately 150 pounds, or c) approximately25 pounds to approximately 75 pounds.

In some aspects, the processor is further configured to: compare theload data with additional load data detected by a set of additionalsensors coupled with additional rod reducers; and provide an indicatorof relative loading of the rod reducer as compared with at least one ofthe additional rod reducers in the set.

In particular implementations, the indicator of relative loadingindicates whether the rod reducer is more loaded, less loaded or equallyloaded relative to the additional rod reducers in the set.

In some cases, the indicator of relative loading always includes anindicator of a least loaded rod reducer in the set.

In certain aspects, the processor is configured to update the indicatorof relative loading over time as load data for at least one of the rodreducer or the additional rod reducers in the set is updated.

In particular cases, the reduction instrument is configured for use in amulti-level reduction procedure such that the indicator of the load datacomprises an indicator of relative loading of the rod reducer ascompared with a set of additional rod reducers engaged with the spinalrod.

In certain implementations, the spinal fixation system includes a set ofrod reduction instruments having a set of rod reducers engaged with thespinal rod, and the reduction feedback system is communicatively coupledto each of the rod reduction instruments and is configured to receiveload data indicating a load exerted by each rod reducer on the spinalrod.

In some aspects, the set of rod reducers includes up to twenty (20)total rod reducers, arranged in subsets of ten (10) on each side of thepatient's spine.

In particular cases, the reduction feedback system is further configuredto provide an indicator of reduction order for the set of rod reductioninstruments based on the received load data.

In certain aspects, the indicator of reduction order includesinstructions for multi-step reduction of the set of rod reductioninstruments.

In some implementations, the reduction feedback system is furtherconfigured to: compare the load data from two or more of the rodreduction instruments in the set with a set of load thresholds; andprovide an indicator prioritizing increased loading of a particular rodreduction instrument over at least one additional rod reductioninstrument based on whether the load data from the two or more rodreduction instruments satisfies the set of load thresholds.

In certain cases, the set of load thresholds include absolute loadingthresholds for each of the two or more rod reduction instruments.

In particular aspects, absolute loading thresholds vary based on atleast one of: a) the location of a given rod reduction instrument alongthe patient's spine, b) the patient's anatomy, or c) the patient's bonequality.

In some implementations, the set of load thresholds include relativeloading thresholds for each of the two or more rod reductioninstruments.

In certain aspects, the reduction feedback system includes anelectronics compartment physically coupled with the rod reducer, theelectronics compartment having at least one of a visual indicationsystem or a tactile indication system for providing the indicator of theload data proximate to the rod reducer.

In particular implementations, the tactile indication system include atleast one vibro-tactile actuator.

In some cases, the reduction feedback system further includes acontroller coupled with the electronics compartment and coupled with aset of additional electronics compartments on a set of additional rodreduction instruments in the spinal fixation system, where thecontroller is configured to communicate with the electronics compartmentand the set of additional electronics compartments either wirelessly orvia a hard-wired connection.

In particular aspects, the hard-wired connection comprises a fiber opticconnection.

In certain cases, the visual indication system includes a set of lightsconfigured to be illuminated in at least two distinct patterns toindicate distinctions in the load data, or a display configured toprovide at least two distinct visual indicators of the load data.

In some implementations, the display includes a liquid-crystal display(LCD).

In particular aspects, the rod reduction instrument further includes apower source housed in the electronics compartment and coupled with thevisual indication system or the tactile indication system.

In certain implementations, the sensor is located between the proximalend and the distal end of the rod reducer.

In some cases, the rod reducer includes a multi-section shaft, and thesensor is mounted axially between distinct sections of the multi-sectionshaft.

In particular implementations, the sensor is coupled to the proximal endof the rod reducer.

In certain aspects, the sensor is located in a housing with at least aportion of the reduction feedback system.

In some cases, the sensor includes at least one of: a strain gauge,pressure-sensitive film, or a capacitive sensor.

In particular implementations, the rod reduction instrument furtherincludes a guide assembly configured to couple with the pedicle screwreceiver and receive the rod reducer therein.

In certain cases, the rod reducer is configured to fully seat the spinalrod into the pedicle screw receiver and enable the spinal rod to besecured to the pedicle screw receiver.

In some aspects, the reduction feedback system is located at the rodreducer or at an output device separate from the rod reducer.

In particular implementations, the output device includes at least oneof: a) a user interface, b) a display, c) an audio system, or d) asurgical procedure interface.

In certain cases, in the spinal fixation system, the rod reducer sitswithin a guide assembly that couples with the pedicle screw receiver,where the rod reducer is configured to fully seat the spinal rod intothe pedicle screw receiver and enable the spinal rod to be secured tothe pedicle screw receiver.

In particular aspects, the reduction feedback system includes a housingmounted to the proximal end of each of the rod reducers for providingthe indicator of the load data proximate to each of the rod reducers.

In certain cases, the sensor that is coupled to the instrument and isconfigured to determine data relating to at least one of: the first boneanchor, the rod or the instrument, determines data including load data.

In some implementations, the instrument configured to couple to thefirst bone anchor is a reduction instrument configured to seat the rodwithin the receiver, and the load data includes a load exerted by thereduction instrument on the rod during seating of the rod into thereceiver of the first bone anchor.

In particular aspects, the sensor that is coupled to the instrument isconfigured to determine data relating to at least one of: the first boneanchor, the rod or the instrument, and determines data including atensile load between the rod and the bone anchor when the rod is atleast partially seated within the bone anchor.

In some cases, the sensor that is coupled to the instrument isconfigured to determine data relating to at least one of: the first boneanchor, the rod or the instrument, and determines data includingtorsional force data. In particular aspects, the instrument is a driverconfigured to tighten a lock screw within the receiver and lock the rodrelative to the bone anchor, and the torsional force data includes atorsional force on the lock screw during tightening of the lock screwwithin the receiver. In additional particular aspects, the instrument isa driver configured to seat the rod within the receiver and tighten alock screw within the receiver to thereby lock the rod relative to thebone anchor, and the torsional force data includes a torsional force onthe lock screw during tightening of the lock screw within the receiver.

In certain cases, the instrument configured to couple to the first boneanchor includes: a rod reduction instrument configured to seat the rodwithin the receiver; and a driver configured to be inserted through therod reduction instrument to deliver and tighten a lock screw within thereceiver to lock the rod relative to the bone anchor. In some of theseaspects, the data includes at least one of: a load exerted by thereduction instrument on the rod during seating of the rod into thereceiver of the first bone anchor, or a tensile load between the rod andthe bone anchor when the rod is at least partially seated within thebone anchor. In some additional aspects, the data includes a torsionalforce on the lock screw during tightening of the lock screw within thereceiver.

In particular implementations, the spinal fixation system furtherincludes a navigation system communicatively coupled with the instrumentand configured to detect a position of the instrument. In certain ofthese cases, the navigation system is configured to determine a distancemoved by the instrument when the instrument changes position, and thenavigation system communicates the distance to a processor.

Two or more features described in this disclosure, including thosedescribed in this summary section, may be combined to formimplementations not specifically described herein.

The above presents a simplified summary in order to provide a basicunderstanding of some aspects of the claimed subject matter. Thissummary is not an extensive overview. It is not intended to identify keyor critical elements or to delineate the scope of the claimed subjectmatter. Its sole purpose is to present some concepts in a simplifiedform as a prelude to the more detailed description that is presentedlater.

The details of one or more implementations are set forth in theaccompanying drawings and the description below. Other features, objectsand benefits will be apparent from the description and drawings, andfrom the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of a rod reducer according to variousimplementations.

FIG. 2 shows an additional perspective view of a rod reducer accordingto various implementations.

FIG. 3 and FIG. 4 show distinct side views, respectively, of a rodreducer according to various implementations.

FIG. 5 and FIG. 6 show top and bottom views, respectively, of a sleevefor the rod reducer of FIGS. 3 and 4 .

FIG. 7 shows a perspective view of a spinal fixation system according tovarious implementations.

FIG. 8 shows a distinct perspective view of the spinal fixation systemof FIG. 7 , according to various implementations.

FIG. 9 is a schematic side view of a rod reducer and associatedelectronics according to various implementations.

FIG. 10 is a schematic side view of a rod reducer and associatedelectronics according to various additional implementations.

FIG. 11 is a schematic side view of a rod reducer and associatedelectronics according to various further implementations.

FIG. 12 is a system diagram illustrating a spinal fixation system andinstruments according to various implementations.

FIG. 13 is an example data flow diagram illustrating reduction orderingaccording to various implementations.

FIG. 14 is a side view of a portion of a spinal fixation systemaccording to various implementations.

FIG. 15 is a top view of a visual indication mechanism according tovarious implementations.

FIG. 16 is a schematic view of a visual indication mechanism accordingto various additional implementations.

FIG. 17 shows a side view of an example driver according to variousimplementations.

FIG. 18 shows an exploded perspective view of the example driver of FIG.17 , according to various implementations.

It is noted that the drawings of the various implementations are notnecessarily to scale. The drawings are intended to depict only typicalaspects of the disclosure, and therefore should not be considered aslimiting the scope of the implementations. In the drawings, likenumbering represents like elements between the drawings.

DETAILED DESCRIPTION

Various example embodiments of devices and techniques for rod reductionduring spinal instrumentation procedures are described herein. In theinterest of clarity, not all features of an actual implementation arenecessarily described in this specification. It will of course beappreciated that in the development of any such actual embodiment,numerous implementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which will vary from one implementation toanother. Moreover, it will be appreciated that such a development effortmight be complex and time-consuming, but would nevertheless be a routineundertaking for those of ordinary skill in the art having the benefit ofthis disclosure. The rod reduction instruments and related systems,program products and methods described herein boast a variety ofinventive features and components that warrant patent protection, bothindividually and in combination.

It is to be understood that any given elements of the disclosedembodiments of the invention may be embodied in a single structure, asingle step, a single substance, or the like. Similarly, a given elementof the disclosed embodiment may be embodied in multiple structures,steps, substances, or the like.

This disclosure provides, at least in part, a rod reduction instrument,related fixation systems, methods and monitoring systems thatbeneficially incorporate a reduction feedback system to enhance efficacyof spinal fixation procedures, as well as mitigate opportunity foroperator (e.g., surgeon) error in performing such procedures. Thevarious disclosed implementations can improve patient outcomes whencompared with conventional spinal fixation procedures. The disclosedimplementations can provide real-time and/or post-operative feedback onreduction procedures, enhancing both current procedural outcomes as wellas future surgical outcomes. In particular cases, the reduction feedbacksystem can provide information to an operator regarding desiredreduction ordering in a multi-level reduction procedure, therebymitigating or avoiding overloading of instruments at any given timeduring the procedure.

Commonly labeled components in the FIGURES are considered to besubstantially equivalent components for the purposes of illustration,and redundant discussion of those components is omitted for clarity.

FIGS. 1 and 2 illustrate perspective views of example rod reductioninstruments, or reducers, according to various implementations. It isunderstood that the disclosed implementations can be applied to a numberof rod reduction instruments in various form factors. For example,additional rod reduction instruments such as those disclosed in U.S.Pat. No. 10,136,927 (entirely incorporated by reference herein) canbenefit from the various disclosed implementations. In variousimplementations, the example rod reduction instruments (reducers) areused during the installation of a fixation construct 10 onto the spineof a patient. The fixation construct 10 includes anchor members 12connected by a fixation rod 14 locked to each anchor 12. An anchor 12 isimplanted in each vertebra to be fixed by the construct 10. For example,two anchors 12 may be used to fix two vertebrae together; three may beused to fix three vertebrae together; four may be used to fix fourvertebrae together; and so on. Additionally, multiple anchors 12 may beused to fix each vertebrae to adjacent vertebrae (e.g., four anchors 12can be used to couple two vertebrae together). The anchor 12 includes abone anchor 18 and a housing 20 for capturing and locking a fixation rod14. The bone anchor 18 may be a bone screw suitable for stable fixationto vertebral bone (e.g. pedicle or vertebral body), as shown. The boneanchor 18 may also include other fixation devices (e.g. hooks, staples,clamps, etc. . . . ). The housing 20 has a base that attaches with thebone anchor and a pair of upstanding arms that together form a rodchannel 22. The housing also includes a mechanism to lock the fixationrod 14 in position in the rod channel 22. For example, the mechanism mayinclude a locking cap guide and advancement feature disposed on theinterior face of each arm that interacts with a complementary feature ona locking cap. The base may be fixed to the anchor 18 or may be coupledsuch that the housing 20 can rotate in one or more directions (e.g.polyaxial). The housing 20 also includes one or more instrumentengagement features for releasably coupling to one or more instrumentsduring implantation. Example of anchors configured for use with thereducers described herein are shown and described in U.S. Pat. No.9,198,698 (“Minimally Invasive Spinal Fixation System and RelatedMethods”) and U.S. Pat. No. 11,051,861 (“Rod Reduction Assemblies andRelated Methods”), the entire contents of each of which are incorporatedherein by reference. The reducers described herein can be engaged to oneor more of the anchors 12 of the fixation construct 10 to facilitatealignment and advancement of the rod 14 into the rod channel 22 of eachanchor. In particular implementations, the fixation construct 10includes a pedicle screw.

Now with reference to FIGS. 1-6 , a rod reducer (or simply, reducer) 100according to one example embodiment is illustrated. The reducer 100 isconfigured to couple to both arms of anchor 12 and impart a downwardforce on the rod 14. The downward force on the rod acts to draw the rod14 and anchor housing 20 together until the rod 14 fully seats in therod channel 22. A locking mechanism, such as locking cap may then be atleast partially engaged to capture the rod 14 in the housing 20 prior todecoupling the reducer 100 from the anchor 12. The reducer 100 includesa coupling unit 102 (FIG. 2 ) that connects to the anchor 12 and atranslation unit 104 (FIG. 2 ) that translates relative to the couplingunit 102 to urge the rod 14 towards the anchor.

The coupling unit 102 includes a base member 106 and first and secondattachment arms 108 that are pivotally coupled with the base member 106.The base member 106 is an elongated, generally tubular member having aproximal portion 110, a central portion 112, a distal portion 114, and acentral lumen 116 (FIG. 6 ) extending longitudinally through the entirelength of the base member 106. The proximal portion 110 includes ahandle 118 that provides a gripping area for a user to grip the reducer100. Above the handle 118 is a head 124 (FIGS. 1-2 ) that allows thecoupling of other instruments with the reducer 100. The head 124 may beconfigured to mimic the proximal end of minimally invasive screw guidessuch that any instruments that engage or couple with the guides may alsoengage or couple with the reducer 100 (for example, vertebral bodyderotation assemblies, counter torques, etc. . . . ). Not shown, theproximal portion 110 can include a threaded portion formed on theinterior of the proximal portion 110 (i.e. the proximal end of the lumen116) for threadedly engaging the translating unit 104. In certainimplementations, a drive knob 170 is located between the proximalportion 110 and the central portion 112.

FIGS. 7 and 8 illustrate a spinal fixation system 210 configured forintroducing and building a posterior spinal fixation construct such asthat described above, according to one example embodiment. According toone example, the spinal fixation system 210 includes a pedicle screw212, an elongated spinal rod 214, and a guide assembly 216. Pediclescrews 212 are inserted bilaterally or unilaterally into multiplevertebra across one or more levels. In additional implementations, afixation anchor (such as those described in U.S. Pat. No. 9,198,698,previously incorporated by reference herein) can be utilized in place ofpedicle screw 212 in one or more vertebra. The spinal fixation system210 may further include any of a variety of instruments configured toperform the installation and assembly of the spinal fixation construct,including by way of example a reduction instrument (also called areducer) 218 shown in FIGS. 7 and 8 , as well as rod inserters,compression instruments, lock screw inserters, guide adjusters, tapguides, and dilators, of which various embodiments are described infurther detail in U.S. Pat. No. 9,198,698, previously incorporated byreference herein.

FIG. 9 shows an example implementation of a rod reduction instrument (orsimply, instrument) 300 according to various implementations. Asillustrated in FIG. 9 , the instrument 300 includes a rod reducer (orsimply, reducer) 302, which can be similar in form and/or function tothe reducer(s) described according to any implementation herein, e.g.,reducer 100 and/or reducer 218. In particular implementations, thereducer 302 has a proximal end 304 and a distal end 306. The distal end306 is configured to engage a spinal rod for seating the spinal rod intoa pedicle screw receiver (e.g., as described with respect to FIGS. 1-4). In various implementations, the rod reducer 302 is configured tofully seat the spinal rod (e.g., spinal rod 214 in FIG. 8 ) into thepedicle screw receiver (e.g., the receiver of the pedicle screw 212 inFIG. 8 , also referred to as the rod channel 22 in FIG. 2 ).

In particular implementations, the instrument 300 includes a sensor 308configured to detect a load exerted by the rod reducer 302 on the spinalrod during seating of the spinal rod in the pedicle screw receiver. Inparticular examples, the sensor 308 includes one or more of: a straingauge, a pressure-sensitive film, or a capacitive sensor. In variousimplementations, the sensor 308 is configured to sense a load appliedvia the rod reducer 302, e.g., on the spinal rod. In certain examples,the sensor 308 is configured to indicate a pressure and/or torqueapplied by the rod reducer 302, e.g., on the spinal rod.

In certain implementations, the sensor 308 is configured to determinedata relating to at least one of: a bone anchor (e.g., anchor 12 inFIGS. 1-6 and/or pedicle screw 212 in FIGS. 7 and 8 ), a spinal rod(e.g., rod 14 in FIGS. 1-6 and/or spinal rod 214 in FIGS. 7 and 8 ), orthe reducer 302. In certain examples, the sensor 308 provides load dataincluding a tensile load between the rod and the bone anchor when therod is at least partially seated within the bone anchor. In additionalexamples, the sensor 308 provides load data including torsional forcedata.

In particular implementations, the sensor 308 is located between theproximal end 304 and the distal end 306 of the rod reducer 302. Forexample, as illustrated in FIG. 9 , the reducer 302 includes amulti-section shaft 310, including a first section 312 and a secondsection 314, and the sensor 308 is mounted axially between the sections312, 314. In additional examples, such as illustrated in FIG. 10 , thesensor 308 is coupled to the proximal end 304 of the rod reducer 302,e.g., on an end of the rod reducer 302.

In particular implementations, a housing 316 is coupled to the reducer302, e.g., at the proximal end 304 of the reducer 302. In certain cases,the housing 316 includes electronics 318 as described herein. Inadditional implementations, the electronics 318 are configured tocommunicate (e.g., wirelessly and/or hard-wired connection) with aremote spinal fixation management system. In particular cases, theelectronics 318 include at least one portion of a reduction feedbacksystem 320.

The sensor 308 is coupled with the reduction feedback system 320 that isconfigured to: a) receive load data indicating the load exerted by therod reducer 302 on the spinal rod from the sensor; and b) provide anindicator of the load data such that the indicator is detectable by anoperator of the instrument 300. As described herein and indicated inphantom in FIG. 9 , the reduction feedback system 320 can be at leastpartially disposed in the housing 316 mounted to the proximal end 304 ofthe reducer 302. In additional implementations, the reduction feedbacksystem 320 is at least partially located in a centralized spinalfixation management system, described further herein.

In certain cases, the housing 316 is modular and/or disposable. That is,in certain cases, the housing 316 substantially contains the reductionfeedback system 320 and is able to be selectively coupled and/ordecoupled with the proximal end 304 of the reducer (e.g., with selectivecouplers such as male/female threading, snap-fit connectors, pressure orforce-fit connectors, adhesive(s), etc.). In certain of these cases, thereduction feedback system 320 is disposable, that is, intended forone-time use during a spinal fixation procedure. In these examples, thereduction feedback system 320 can include onboard electronics that areintended for limited usage, e.g., sensor(s) 308, power, and signalconditioning electronics such as an interface circuit to process andoutput a signal. In certain cases, the interface circuit includes asignal processor such as a digital signal processor (DSP), a logicengine to filter/condition the signal, and a controller to controlonboard functions such as displays and transmission of signals toexternal components such as an external receiver. In particularexamples, the housing 316 is selectively coupled to an existing nut onthe proximal end 304 of the reducer 302. In additional examples, thehousing 316 is selectively coupled to the central lumen 116 or anotherportion of the body of the reducer 302.

In certain examples, as illustrated in FIG. 11 , the sensor 308 islocated within the housing 316 with at least a portion of the reductionfeedback system 320. In these implementations, the sensor 308 can bedirectly coupled with the reduction feedback system 320, or at least theportion of the reduction feedback system 320 that is present in thehousing 316. In particular cases, the electronics 318 are powered by anonboard power source 321 at the housing 316 (e.g., one or morebatteries, charging devices and/or hard-wired power sources).

A schematic depiction of the reduction feedback system 320, includingdata flows related to components that interact with the system 320, isillustrated in FIG. 12 . As described herein, the reduction feedbacksystem 320 can function as an onboard (e.g., on instrument 300) systemand/or a physically separate system (e.g., coupled via a wireless and/orhard wired connection). In certain cases, as described herein, thereduction feedback system 320 is hosted, or otherwise executed as partof a spinal fixation system 400, for example, as described in U.S.patent application Ser. No. 16/562,411 (Systems and Methods for SpinalSurgical Procedures), herein incorporated by reference in its entirety.

In particular implementations, the reduction feedback system 320includes a controller 322 (e.g., one or more microcontrollers), thatincludes at least one processor (PU) 324 (such as one or moremicroprocessors) and is coupled with or contains a memory 326 (e.g.,including one or more storage components such as memory chips and/orchipsets). The memory 326 stores instructions (e.g., reduction feedback(RF) instructions 328) which when executed by the PU(s) 324 cause the PU324 to: i) compare the load data obtained from the sensor 308 with aload threshold for the reducer 302; and ii) provide an indicator thatthe load data satisfies or does not satisfy the load threshold for thereducer 302. In particular cases, the load threshold includes a loadrange for the reducer 302 that is indicative of a desired loading of theanchor (e.g., anchor 12, FIG. 1 , or pedicle screw 212, FIGS. 7, 8 ). Invarious implementations, the load threshold includes a range with anupper and lower bound, which can account for some variation inmeasurement based on a known measurement margin of error, e.g., of thesensor 308. In additional implementations, the load threshold includes aload value that accounts for a known measurement error, e.g., by one,two, or three percent. In certain implementations, the load threshold isbased at least in part on a model that correlates clinical datarepresenting patient-specific bone quality with screw pullout. Thisclinical data can be engrained in a model stored in the reductionfeedback instructions 328, and can be updatable, e.g., as further databecomes available.

In particular implementations, the load data at least partiallyrepresents an amount of torque applied to a lock screw during tighteningof the lock screw within the pedicle screw receiver (FIG. 8 ) and acompressive force applied to the reducer 302. In certain of these cases,e.g., where the load data does not satisfy the load threshold, theindicator can include an indicator of an amount that the torque appliedto the spinal rod should be modified to satisfy the load threshold forthe reducer 302.

In particular implementations, the load threshold(s) defines a maximumacceptable load exerted by the reducer 302 on the spinal rod 214 (FIG. 8) during seating of the spinal rod in the receiver of the pedicle screw212 (FIG. 8 ), also referred to as the rod channel 22 (FIG. 2 ). Incertain cases, the maximum acceptable load is one of: a) approximately50 pounds to approximately 250 pounds, b) approximately 25 pounds toapproximately 150 pounds, or c) approximately 25 pounds to approximately75 pounds. In certain cases, the maximum acceptable load ranges (a)-(c)are combinable, e.g., approximately 50 pounds to approximately 150pounds, approximately 25 pounds to approximately 250 pounds, etc.

With continuing reference to FIG. 12 , an example depiction of areduction feedback system 320 for managing a set of rod reducers 302 a,302 b, 302 c is illustrated. In these cases, the reduction feedbacksystem 320 can be part of a spinal fixation system 400 that isconfigured to manage reducers 302 in a multi-level reduction procedure,e.g., where two or more vertebral adjustments are made along a patient'sspine. In various implementations, a set of rod reducers 302 are engagedwith the spinal rod, and the reduction feedback system 320 iscommunicatively coupled to each of the rod reduction instruments (e.g.,wirelessly or via hard-wired means) and is configured to receive loaddata indicating a load exerted by each rod reducer 302 on the spinalrod. This depiction includes a few rod reducers 302 a, 302 b, 302 c forsimplicity of illustration, but it is understood that the set of rodreducers can include up to twenty (20) total rod reducers, arranged insubsets of ten (10) on each side of the patient's spine. FIG. 14illustrates an example implementation depicting six reducers 302 a-farranged on one side of a patient's spine, which during an alignmentprocedure, would correspond with six additional reducers 302 (not shown)on the opposite side of the patient's spine (for a total of twelve (12)reducers 302).

In particular implementations, the reduction feedback system 320 iscoupled with sensors 308 a, 308 b, 308 c, etc., either directly (such asvia a wireless connection or hard-wired connection), or via the onboardreduction feedback system 320 at each of the reducers 302 a, 302 b, 302c, etc. In certain cases, the reducers 302 (including sensors 308) areconfigured to communicate with the reduction feedback system 320 via acommunications device, e.g., in electronics 318 and/or at spinalfixation system 400 (FIG. 12 ). The communications device(s) can includeone or more transmitters and/or receivers (e.g., wireless and/orhard-wired transmitters/receivers). In various implementations, thecommunication devices are configured for a plurality of communicationprotocols, e.g., wireless protocols such as WiFi, Bluetooth, BLE,Zigbee, etc., as well as radio communication and intercomcommunications, and/or a hardwired connection (e.g., fiber opticconnection).

In any case, the reduction feedback system 320 (and particularly, PU(s)324) is configured to compare the load data received from one or moresensors 308 with corresponding load thresholds for those sensors 308 inorder to determine whether one or more reducers 302 is appropriatelyloaded (e.g., over or under loaded). FIG. 13 illustrates an example datastructure of the RF instructions 328 for comparing load data 340 with aset of thresholds 350 in order to determine: a) whether a particularreducer 302 is under or over loaded, and b) a reduction order foradjusting the load on a plurality of reducers 302. Based on the loaddata 340, the RF instructions 328 provide reduction (sequencing)instructions 360, such as an identifier of one or more reducers 302 andan amount of load adjustment. In certain cases, the reductioninstructions 360 include reduction sequencing instructions, such aswhere a plurality of load data 340 are obtained as part of a multi-levelreduction procedure.

With reference to FIGS. 12-14 , in various implementations, thereduction feedback system 320 is configured to compare load data 340from each of a plurality of sensors 308 and provide reductioninstructions 360, which can include an indicator of relative loadingbetween at least two of the reducers 302. For example, the indicator ofrelative loading can indicate whether a given rod reducer (e.g., reducer302 b) is more loaded, less loaded or equally loaded relative to any oneof or all of the additional rod reducers (e.g., reducers 302 a, 302 c)in the set. In various implementations, load data 340 is continuously,or periodically, updated during the alignment procedure, such that newload data 340 is processed by the reduction feedback system 320 for anextended period during the procedure. In particular cases, load data 340is updated every time a change in load at one of the sensors 308 isdetected, e.g., at every adjustment by the surgeon. In these cases, thereduction instructions 360 are continuously updated to reflect therelative load on each reducer 302 in the set. In exampleimplementations, the indicator of relative loading always includes anindicator of a least loaded rod reducer 302 in the set of reducers, suchthat the system 320 is configured to update the indicator of relativeloading over time as load data for at least one of the reducers 302 inthe set is updated.

As illustrated in FIG. 13 , the reduction instructions 360 can includean indicator of reduction order (or sequencing) for the set of reducers302 a, 302 b, 302 c, etc. based on the received load data 340. Forexample, the indicator of reduction order can include reductioninstructions 360 for multi-step reduction of the set of reducers 302. Inparticular, FIG. 13 illustrates an example implementation where thesystem 320: i) compares the load data 340 from two or more reductioninstruments (e.g., reducers 302) with a set of thresholds 350, and ii)provides an indicator prioritizing modified loading (e.g., increased ordecreased loading) of a particular reduction instrument (e.g., reducer302 b) over at least one additional reduction instrument (e.g., reducer302 a) based on whether the load data 340 from the two or more reductioninstruments 302 a, 302 b, satisfies the set of load thresholds. In somecases, the thresholds 350 include absolute loading thresholds (e.g.,Absolute Loading Thresholds 1, 2, 3) for each of the reducers 302. Theseabsolute loading thresholds can represent a minimum and/or maximumacceptable load value for the load data 340 (e.g., as detected bysensor(s) 308). In certain cases, absolute loading thresholds vary basedon at least one of: a) location of a given rod reduction instrument(e.g., reducer 302) along the patient's spine, b) the patient's anatomy(e.g., curvature of the spine), or c) the patient's bone quality. Forexample, the RF instructions 328 can be adjusted or otherwise tailoredaccording to patient-specific inputs 370, which can includecharacteristics of the patient (e.g., physiological and/or anatomicalcharacteristics such as spacing between vertebrae, angulation of one ormore sections of the patient's spine, etc.), as well as the patient'sbone quality (e.g., on a mechanical bone quality scale such as a T-score(comparing relative health to a standard), or a quality indicatorderived from a bone scan such as a CT scan or MRI). For example,absolute loading thresholds can be adjusted based on the patient's bonequality (e.g., lower maximum absolute load threshold for lower bonequality), and/or the angulation of adjacent vertebrae in which thereducers 302 are operating (e.g., higher minimum absolute load thresholdfor higher angulation value). Additionally, the RF instructions 328 canbe adjusted based on the location of a given reducer 302 along thespine, e.g., with distinct absolute loading thresholds at L2 versus L4.

Even further, the load thresholds 350 can include relative loadingthresholds (e.g., Relative Load Threshold 1, Relative Load Threshold 2)for each of the two or more rod reduction instruments (e.g., reducers302 a, 302 b, 302 c, etc.). In these cases, the relative loadingthresholds can define a maximum allowable difference in loading betweenany two reducers 302, and/or between any two adjacent reducers (e.g.,between reducers 302 a and 302 b, or reducers 302 d and 302 e, FIG. 14). These relative loading thresholds can be used to determine areduction order, e.g., to prioritize loading a particular reducer 302 aover another reducer 302 c. In the example shown in FIG. 13 , load data340 is processed using absolute load thresholds prior to relative loadthresholds, but this order can be reversed in various implementations.In additional implementations, loading thresholds and relative loads canbe used to construct a reduction order, e.g., for instructing a usersuch as a surgeon or other medical professional. In some cases, the loaddata 340 for reducer(s) 302 is analyzed based on one or more of: i) athreshold for a given reducer 302 or an aggregate threshold for a groupof reducers 302, to avoid exceeding a threshold for reducer(s) 302; ii)relative loading between reducers 302, to avoid a loading differencebetween any two or more reducers 302 exceeding a difference threshold;iii) an upper and/or lower reduction bound during manipulation of areducer 302, or iv) to comply with a reduction order prescribed bypre-operation planning. In certain cases, after comparing the load data340 for two or more reducers 302 a, 302 b, 302 c, etc., the system 320provides at least one load adjustment (e.g., Load Adjustment 1, LoadAdjustment 2, etc.), which is placed in an ordered listing for use asreduction (sequencing) instructions 360. For example, reduction(sequencing) instructions 360 can include Load Adjustment 1 (e.g.,adjust torque on reducer 302 b with clockwise quarter turn or X lbs ofpressure increase), followed by Load Adjustment 2 (e.g., after LoadAdjustment 1: adjust torque on reducer 302 a with counter-clockwise halfturn or Y lbs of pressure decrease).

In various implementations, due to the interrelated nature of theloading across different reduction instruments (e.g., reducers 302 a,302 b, etc.), reduction sequencing instructions 360 can include amulti-reducer sequence that in certain cases involves adjusting the loadon a given reducer 302 more than once in a complete sequence. Forexample, the reduction sequencing instructions 360 can includeinstructions to first adjust the load on a first reducer 302 a by anamount that does not fully seat the rod into the anchor receiver, thenadjust the load on a second reducer 302 b, and subsequently furtheradjust the load on the first reducer 302 by an amount that fully seatsthe rod into the anchor receiver.

In particular implementations, e.g., as illustrated in FIG. 12 , thespinal fixation system 400 can further include an interface 380 thatenables interaction between the reduction feedback system 320 and thesurgeon, medical professional(s) and/or other operators in the spinalfixation procedure room. In some cases, the spinal fixation system 400communicates with the reducer(s) 302 via a communications device 390such as the wireless and/or hard wired communication devices describedherein. The interface(s) 380 can include any conventional visual,tactile and/or auditory interface that can enable communication ofreduction feedback information to the surgeon, medical professionaland/or operator during the spinal fixation procedure. In certain cases,the interface(s) 380 include a graphical user interface (GUI), which caninclude a liquid crystal display (LCD), one or more touch screens,virtual medical assistant systems (e.g., voice-based command system),etc. In particular cases, as illustrated in FIGS. 9-11 , theinterface(s) 380 can include a visual indication system 410 and/atactile indication system 420 for providing an indicator of the loaddata 340 (FIG. 13 ) detected by sensors 308 at the reducer(s) 302. Thatis, in certain implementations, at least a portion of the visualindication system 410 and/or tactile indication system 420 is located atthe reducer 302 (e.g., at each reducer, coupled with housing 316). Inadditional implementations, a portion of the visual indication system410 and/or tactile indication system 420 can be located at a centralizedinterface, e.g., interface 380 at the spinal fixation system 400.

In certain implementations, the tactile indication system 420 includesat least one vibro-tactile actuator, which can be configured to conveyto the surgeon (or other medical professional or operator) that areducer 302 requires further loading and/or is approaching anover-loaded condition. For example, the tactile indication system 420can be configured to trigger a vibrational cue (e.g., by vibrating thehousing 316) when the loading for a given reducer 302 is approaching amaximum absolute loading threshold. In some cases, the tactileindication system 420 can be integrated in housing 316 or otherwiseconnected with the housing 316 to initiate a vibrational response to theload data from a corresponding sensor 308 approaching and/or exceeding amaximum absolute loading threshold. In additional cases, the tactileindication system 420 is configured to provide distinct vibrational cuesof the loading of a reducer, e.g., a first set of vibrational cuesindicating under-loading, and a second set of vibrational cuesindicating over-loading or approaching a loading limit.

FIG. 15 shows an example of a proximal end 304 of a reducer 302 (e.g.,proximal end of housing 316) that includes a visual indication system410 having a set of lights 430 configured to be illuminated in at leasttwo distinct patterns to indicate distinctions in the load data for thereducer 302. This example shows lights 430 of differing colors, but anyprogressive lighting arrangement can be used to provide the distinctpatterns. For example, an annular arrangement of lights 430 asillustrated in FIG. 15 can be configured to provide distinctions incolor, e.g., green indicating desired loading, yellow approachingover-loading, red indicating over-loading. In some cases, this annulararrangement of lights 430 has a same or similar color, but can beilluminated in at least two distinct patterns (to indicate over/underloading). An annular lighted arrangement is only one of the variouspossible arrangements in keeping with the implementations herein, and assuch, linear light arrays, light bars, distinctions in light intensity,etc., can be used to visually indicate loading for a given reducer 302.

FIG. 16 illustrates another example of a visual indication system 410(e.g., via interface 380), including for example, a reduction display450 that includes a bar graph showing load levels (e.g., on a scale ofzero to twenty) across a set of ten (10) distinct reducers 302. In thisexample, the bar graph can be dynamically updated as changes in loaddata are detected for one or more reducers 302, such that the viewer(e.g., surgeon, medical professional or other operator) can see whichreducers 302 are least loaded, or otherwise can withstand increasedloading, and which reducer(s) 302 are approaching an upper limit forloading. In certain of these cases, the reduction display 450 canutilize distinctions in color (not shown) to indicate sequencing orotherwise supplement the indication of the least loaded reducer 302,e.g., the first reducer 302 that should undergo an increase in loading.

Returning to FIG. 12 , in various additional implementations(illustrated in phantom as optional), the reduction feedback system 320is further coupled with one or more additional fixation instrument(s)500, which can include one or more sensors 308, such as the load sensorsdescribed herein. In particular cases, the fixation instrument 500includes a driver configured to tighten a lock screw within a boneanchor receiver (e.g., receiver in bone anchor (e.g., anchor 12 in FIGS.1-6 and/or pedicle screw 212 in FIGS. 7 and 8 ), and lock a rod (e.g.,rod 14 in FIGS. 1-6 and/or spinal rod 214 in FIGS. 7 and 8 ) relative tothe bone anchor. Examples of such fixation instruments are provided inUS Patent Application Publication No. 2020/0297393 (U.S. applicationSer. No. 16/898,713), which is incorporated by reference in itsentirety. In further particular cases, the fixation instrument 500includes a guide (also called a “guide tube” in some cases) for definingthe trajectory of instruments and/or screws during a spinal surgery.Examples of fixation instruments such as guides and guide tubes areprovided in US Patent Application Publication No. 2021/0085485 (U.S.application Ser. No. 16/995,602), which is incorporated by reference inits entirety.

With reference to additional fixation instruments, FIGS. 17 and 18illustrate side and exploded perspective views, respectively, of anexample of a driver 600 according to various implementations. In thiscase, the driver 600 has a proximal end 610 and a distal end 620, wherethe distal end 620 is configured to engage with and tighten a lockscrew. A sensor 308 is shown located coaxially with the driver 600,e.g., mounted between or within sections 630A, 630B of the driver shaft630. In certain cases, the housing for the sensor 308 includes one ormore mating features 640 for coupling with complementary mating features650 in the shaft 630. In certain additional cases, a housing 316 mountedto the shaft 630, e.g., near the proximal end 610, includes one or moreadditional sensors 308 and/or electronics 318, power source(s) 321,and/or indication systems 410, 420 such as those described withreference to FIGS. 9-11 . In the example of the driver 600 depicted inFIGS. 17 and 18 , the sensor(s) 308 can be configured to providetorsional force data indicating a torsional force applied on the lockscrew during tightening of the lock screw within the receiver, e.g., inthe process of locking the rod relative to the bone anchor. In certaincases, the driver (or, driver instrument) 600 is configured to becoupled with the rod reducer(s) 302 described herein. In particularimplementations, the driver 600 can be configured to be inserted throughthe rod reducer 302 to deliver and tighten a lock screw within thereceiver to lock the rod relative to the bone anchor. According tocertain implementations, the sensor(s) 308 in driver 600 can beconfigured to provide torsional force data about a torsional forceapplied by the driver 600 on the lock screw. In some examples, thedriver 600 can be deployed as a “finishing” or “final tightening” driverthat is configured to tighten the lock screw in its final or finishingphase. In such cases, the sensor(s) 308 in the driver 600 can beconfigured to provide data about the torsional force applied by thedriver 600 on the lock screw in the final or finishing phase.

In still further implementations, the sensor(s) 308 in the fixationinstruments 500 (e.g., driver 600, rod reducer 302 and/or a guide tube)described herein, can be configured to provide data about a load exertedby the fixation instrument 500 on the rod during seating of the rod intothe receiver of the bone anchor, and/or data about a tensile loadbetween the rod and the bone anchor when the rod is at least partiallyseated within the bone anchor. In certain implementations, both torqueand compression data are recorded by sensor(s) 308 on fixationinstruments 500 and provided to the reduction feedback system 320 foranalysis and/or action (e.g., to adjust reduction instructions). It isunderstood that torque and/or compression data detected by sensors 308,e.g., such as in a sensor mounted to the driver 600 and/or rod reducer302, can represent an inferred or correlated indicator of the torqueand/or compression applied to a device or component not physically incontact with the sensor 308. For example, the sensor 308 on aninstrument 500 (e.g., driver 600) can be configured to detect torque atthe instrument 500, while that torque is being translated to a lockscrew in contact with the distal end of the instrument. Similarly, thesensor 308 on an instrument 500 (e.g., rod reducer 302) can detectcompression at the instrument 500, while that compression is beingtranslated to a rod.

In additional implementations, one or more fixation instrumentsdescribed herein, e.g., rod reducers 302, fixation instrument(s) 500,etc. can be communicatively coupled with a navigation system (e.g., viaspinal fixation system 400) that is configured to detect a position ofthe instrument(s). In one example depiction in FIG. 12 , a navigationsystem 700 (indicated in phantom as optional) is coupled with thereduction feedback system 320 in order to provide navigation informationabout a position of instruments. For example, the navigation system 700can include an optical tracking system such as a camera or laser-basedtracking system, a Global Positioning System (GPS), an inertialmeasurement unit (IMU), etc. In certain cases, the navigation system 700is configured to determine a distance moved by the instrument when theinstrument changes position, which the navigation system 700communicates to the reduction feedback system 400. One or morecomponents of a navigation system 700 can be located within or otherwiseintegrated with a housing, e.g., housing 316 (FIGS. 9-11 ), that ismounted to or otherwise coupled with one or more of the reductioninstruments. For example, components of a navigation system such as aGPS and/or IMU can be located in a housing 316. In certain examples, thenavigation system 700 and/or a portion thereof is fixed to a portion ofthe rod reducer(s) 302, fixation instrument(s) 500, etc., and isphysically separated from the housing 316. In some of these cases, e.g.,where the housing 316 and/or other electronics packages are modular, thenavigation system 700 can remain independently coupled to the rodreducer 302, fixation instrument 500 or other instrument. In additionalimplementations, the spinal fixation system 400 includes or is coupledwith a navigation system 700 that is external to the housing 316 and/orthe reduction instruments.

With reference to FIGS. 12 and 13 , in additional implementations, thereduction feedback system 320 is configured to provide post-operativedata and analysis of reduction procedure and/or device usage, e.g., toenhance future procedures and/or diagnose inefficiencies in a pastprocedure. In certain implementations, the reduction feedback system 320is configured to update the RF instructions 328 based on identifiedinefficiencies or errors in reduction sequencing and/or device usageduring a given procedure. In particular implementations, the reductionfeedback system 320 includes a logic engine configured to modify RFinstructions 328 iteratively, e.g., on a procedure-by-procedure basis.

As noted herein, the reduction devices, reduction feedback systems andspinal fixation systems disclosed according to various implementationsprovide numerous benefits relative to conventional spinal fixationdevices and systems. For example, the disclosed devices, systems,feedback systems, and methods can enhance efficacy of spinal fixationprocedures, as well as mitigate operator (e.g., surgeon) error inperforming such procedures. Various disclosed implementations canimprove patient outcomes when compared with conventional spinal fixationprocedures. Additionally, the disclosed implementations can providereal-time and/or post-operative feedback on reduction procedures,enhancing both current procedural outcomes as well as future surgicaloutcomes. In certain implementations, the reduction feedback system canprovide information to an operator regarding desired reduction orderingin a multi-level reduction procedure, thereby mitigating or avoidingoverloading of instruments at any given time during the procedure.

The functionality described herein, or portions thereof, and its variousmodifications (hereinafter “the functions”) can be implemented, at leastin part, via a computer program product, e.g., a computer programtangibly embodied in an information carrier, such as one or morenon-transitory machine-readable media, for execution by, or to controlthe operation of, one or more data processing apparatus, e.g., aprogrammable processor, a computer, multiple computers, and/orprogrammable logic components.

A computer program can be written in any form of programming language,including compiled or interpreted languages, and it can be deployed inany form, including as a stand-alone program or as a module, component,subroutine, or other unit suitable for use in a computing environment. Acomputer program can be deployed to be executed on one computer or onmultiple computers at one site or distributed across multiple sites andinterconnected by a network.

Actions associated with implementing all or part of the functions can beperformed by one or more programmable processors executing one or morecomputer programs to perform the functions of the calibration process.All or part of the functions can be implemented as, special purposelogic circuitry, e.g., an FPGA and/or an ASIC (application-specificintegrated circuit). Processors suitable for the execution of a computerprogram include, by way of example, both general and special purposemicroprocessors, and any one or more processors of any kind of digitalcomputer. Generally, a processor will receive instructions and data froma read-only memory or a random access memory or both. Components of acomputer include a processor for executing instructions and one or morememory devices for storing instructions and data.

In various implementations, components described as being “coupled” toone another can be joined along one or more interfaces. In someimplementations, these interfaces can include junctions between distinctcomponents, and in other cases, these interfaces can include a solidlyand/or integrally formed interconnection. That is, in some cases,components that are “coupled” to one another can be simultaneouslyformed to define a single continuous member. However, in otherimplementations, these coupled components can be formed as separatemembers and be subsequently joined through known processes (e.g.,soldering, fastening, ultrasonic welding, bonding). In variousimplementations, electronic components described as being “coupled” canbe linked via conventional hard-wired and/or wireless means such thatthese electronic components can communicate data with one another.Additionally, sub-components within a given component can be consideredto be linked via conventional pathways, which may not necessarily beillustrated.

While inventive features described herein have been described in termsof preferred embodiments for achieving the objectives, it will beappreciated by those skilled in the art that variations may beaccomplished in view of these teachings without deviating from thespirit or scope of the invention. Also, while this invention has beendescribed according to a preferred use in spinal applications, it willbe appreciated that it may be applied to various other uses desiringsurgical fixation, for example, the fixation of long bones.

A number of implementations have been described. Nevertheless, it willbe understood that additional modifications may be made withoutdeparting from the scope of the inventive concepts described herein,and, accordingly, other implementations are within the scope of thefollowing claims.

We claim:
 1. A rod reduction instrument adapted for use with a spinalfixation system, the rod reduction instrument comprising: a rod reducerhaving a proximal end and a distal end, wherein the distal end of therod reducer is configured to engage a spinal rod for seating the spinalrod into a pedicle screw receiver; a sensor configured to detect a loadexerted by the rod reducer on the spinal rod during seating of thespinal rod in the pedicle screw receiver; and a reduction feedbacksystem coupled with the sensor, the reduction feedback system configuredto: receive load data indicating the load exerted by the rod reducer onthe spinal rod from the sensor; compare the load data with a loadthreshold for the rod reducer; and provide an indicator of the load datathat is detectable by an operator of the rod reduction instrument,wherein the indicator of the load data includes an indicator that theload data satisfies or does not satisfy the load threshold for the rodreducer, the reduction feedback system further configured to: comparethe load data with additional load data detected by a set of additionalsensors coupled with a set of additional rod reducers; and provide anindicator of relative loading of the rod reducer as compared with atleast one of the additional rod reducers in the set, wherein theindicator of relative loading indicates whether the rod reducer is moreloaded, less loaded or equally loaded relative to the additional rodreducers in the set, wherein the reduction feedback system is configuredto update the indicator of relative loading over time as load data forat least one of the rod reducer or the additional rod reducers in theset is updated.
 2. The rod reduction instrument of claim 1, furthercomprising a housing mounted to the proximal end of the rod reducer,wherein the reduction feedback system is disposed within the housing. 3.The rod reduction instrument of claim 1, wherein the load data at leastpartially represents an amount of torque applied to a lock screw duringtightening of the lock screw within the pedicle screw receiver and acompressive force applied to the rod reducer, wherein the indicator thatthe load data satisfies or does not satisfy the load threshold includesan indicator of an amount that the compressive force applied to thespinal rod should be modified to satisfy the load threshold for the rodreducer, wherein the load threshold is based at least in part on a modelthat correlates clinical data representing patient-specific bone qualitywith screw pullout, wherein the model is updatable based on updates tothe clinical data, wherein the load threshold defines a maximumacceptable load exerted by the rod reducer on the spinal rod duringseating of the spinal rod in the pedicle screw receiver, wherein themaximum acceptable load is: a) approximately 50 pounds to approximately250 pounds, b) approximately 25 pounds to approximately 150 pounds, orc) approximately 25 pounds to approximately 75 pound.
 4. The rodreduction instrument of claim 1, wherein the reduction instrument isconfigured for use in a multi-level reduction procedure such that theindicator of the load data comprises the indicator of relative loadingof the rod reducer as compared with the set of additional rod reducersengaged with the spinal rod, wherein the indicator of relative loadingis based on a reducer-specific load threshold, wherein thereducer-specific load threshold varies between the rod reducer and atleast one of the set of additional rod reducers.
 5. The rod reductioninstrument of claim 1, wherein the spinal fixation system furthercomprises a set of rod reduction instruments including the set of rodreducers engaged with the spinal rod, and wherein the reduction feedbacksystem is communicatively coupled to each of the rod reductioninstruments and is configured to receive load data indicating a loadexerted by each rod reducer on the spinal rod.
 6. The rod reductioninstrument of claim 5, wherein the reduction feedback system is furtherconfigured to provide an indicator of reduction order for the set of rodreduction instruments based on the received load data, wherein theindicator of reduction order includes reduction instructions formulti-step reduction of the set of rod reduction instruments.
 7. The rodreduction instrument of claim 6, wherein the sensor is coupled to theproximal end of the rod reducer, or the sensor is located in a housingwith at least a portion of the reduction feedback system, wherein thesensor comprises at least one of: a strain gauge, pressure-sensitivefilm, or a capacitive sensor, and wherein the reduction instructions formulti-step reduction include reduction sequencing instructions defininga multi-reducer sequence that involves adjusting a load on a given rodreduction instrument in the set of rod reduction instruments more thanonce in a complete sequence such that a first adjustment of the givenrod reduction instrument does not fully seat the spinal rod into thepedicle screw receiver and a second, subsequent adjustment of the givenrod reduction instrument fully seats the spinal rod into the pediclescrew receiver.
 8. The rod reduction instrument of claim 5, wherein thereduction feedback system is further configured to: compare the loaddata from two or more of the rod reduction instruments in the set with aset of load thresholds; and provide an indicator prioritizing increasedloading of a particular rod reduction instrument over at least oneadditional rod reduction instrument based on whether the load data fromthe two or more rod reduction instruments satisfies the set of loadthresholds, and wherein a) the set of load thresholds include absoluteloading thresholds for each of the two or more rod reductioninstruments, or b) the set of load thresholds include relative loadingthresholds for each of the two or more rod reduction instruments.
 9. Therod reduction instrument of claim 8, wherein the set of load thresholdsinclude both the absolute loading thresholds for each of the two or morerod reduction instruments and the relative loading thresholds for eachof the two or more rod reduction instruments, wherein the absoluteloading thresholds vary for at least two of the rod reductioninstruments based on at least one of: a location of a rod reductioninstrument along the patient's spine, an anatomical feature of thepatient, or bone quality of the patient.
 10. The rod reductioninstrument of claim 9, wherein the reduction feedback system is furtherconfigured to provide an indicator of reduction order for the set of rodreduction instruments based on whether each of the two or more rodreduction instruments satisfies a corresponding absolute loadingthreshold and a corresponding relative loading threshold, wherein theabsolute loading threshold defines a minimum load and a maximum load fora corresponding rod reduction instrument and wherein the relativeloading threshold defines a maximum difference in loading between two ormore of the set of rod reduction instruments.
 11. The rod reductioninstrument of claim 10, wherein the relative loading threshold furtherdefines a maximum difference in loading between two adjacent rodreduction instruments, and wherein the absolute loading threshold isevaluated prior to the relative loading threshold for at least one ofthe rod reduction instruments in the set of rod reduction instruments.12. The rod reduction instrument of claim 1, wherein the reductionfeedback system comprises an electronics compartment physically coupledwith the rod reducer, the electronics compartment comprising at leastone of a visual indication system or a tactile indication system forproviding the indicator of the load data proximate to the rod reducer,wherein the reduction feedback system further comprises a controllercoupled with the electronics compartment and coupled with a set ofadditional electronics compartments on a set of additional rod reductioninstruments in the spinal fixation system, wherein the controller isconfigured to communicate with the electronics compartment and the setof additional electronics compartments either wirelessly or via ahard-wired connection, wherein the visual indication system includes aset of lights configured to be illuminated in at least two distinctpatterns to indicate distinctions in the load data, or a displayconfigured to provide at least two distinct visual indicators of theload data, the rod reduction instrument further comprising a powersource housed in the electronics compartment and coupled with the visualindication system or the tactile indication system.
 13. The rodreduction instrument of claim 1, wherein the sensor is located betweenthe proximal end and the distal end of the rod reducer, wherein the rodreducer includes a multi-section shaft, and wherein the sensor ismounted axially between distinct sections of the multi-section shaft.14. The rod reduction instrument of claim 1, further comprising a guideassembly configured to couple with the pedicle screw receiver andreceive the rod reducer therein, wherein the rod reducer is configuredto fully seat the spinal rod into the pedicle screw receiver and enablethe spinal rod to be secured to the pedicle screw receiver.
 15. The rodreduction instrument of claim 1, wherein the sensor is directly coupledwith the feedback system and is located in a common housing with thefeedback system, wherein the housing is at least one of modular ordisposable and is coupled with the proximal end of the rod reducer. 16.A spinal fixation monitoring system for use in a spinal fixationprocedure, the system comprising: a plurality of rod reductioninstruments adapted for use with a spinal fixation system, each of therod reduction instruments including: a rod reducer having a proximal endand a distal end, wherein the distal end of the rod reducer isconfigured to engage a spinal rod for seating the spinal rod into acorresponding pedicle screw receiver; and a sensor configured to detecta load exerted by the rod reducer on a portion of the spinal rod duringseating of the spinal rod in the pedicle screw receiver; and a reductionfeedback system coupled with the sensor of each of the rod reductioninstruments, the reduction feedback system configured to: receive loaddata indicating the load exerted by each rod reducer on the portion ofthe spinal rod from a corresponding one of the sensors; compare the loaddata for each of the rod reducers with a corresponding load threshold;for each of the rod reducers: provide an indicator that the load datasatisfies or does not satisfy the load threshold for the rod reducer,the indicator being detectable by an operator of the plurality of rodreduction instruments, provide an indicator of relative loading of afirst rod reducer as compared with at least one additional rod reducerin the plurality of rod reduction instruments, wherein the indicator ofrelative loading indicates whether the first rod reducer is more loaded,less loaded or equally loaded relative to the additional rod reducers inthe plurality of rod reduction instruments, wherein the reductionfeedback system is configured to update the indicator of relativeloading over time as load data for at least one of the first rod reduceror the additional rod reducers in the plurality of rod reductioninstruments is updated.
 17. The system of claim 16, wherein thereduction feedback system comprises a housing mounted to the proximalend of each of the rod reducers for providing the indicator of the loaddata proximate to each of the rod reducers, wherein the housing is atleast one of modular or disposable.